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Biomedical subjects

R Thomssen

Publications and source records attributed to R Thomssen.

At least 19 recordsLinked to original sources
PubMed1992

Association of hepatitis C virus in human sera with beta-lipoprotein.

Hepatitis C virus (HCV)-RNA in sera of patients with viral hepatitis C is supposed to be included, at least partially, into HCV particles. We found that the density of HCV-RNA-carrying material was variable, as determined by sucrose gradient density centrifugation (1.03-1.20 g/cm3). In some of the sera examined HCV-RNA was restricted to low densities between 1.03 and 1.08 g/cm3. In other sera additional densities of HCV-RNA were found distributed over the whole gradient with peaks at 1.12 and 1.17 and at 1.19-1.20 g/cm3. HCV-RNA banding at low densities could be completely co-precipitated with anti-beta lipoprotein, whereas HCV-RNA fractions of higher densities were only partially precipitated or not at all. In 8 of 20 sera directly examined, HCV-RNA could be completely and in 9 sera only partially co-precipitated by anti-beta lipoprotein. In 3 sera no significant precipitation could be observed.

Acute Disease↗
PubMed1992

Genomic variability in the preS1 region and determination of routes of transmission of hepatitis B virus.

On the basis of published sequence data the preS1 attachment region of hepatitis B virus (HBV) appears to be highly variable. Using a novel method for rapid DNA sequencing by the polymerase chain reaction we screened 34 HBV DNA-positive sera for mutations in a variable part of the preS1 region of the HBV genome. The sequence data were used to analyse potential chains of infection, and strongly supported the expected routes of HBV transmission among patient groups. Furthermore, sequence comparisons permitted sub-genotyping of the viruses. In the 22 cases of subtype adw, we found a very low number of point mutations. This shows that the attachment site of HBV is more highly conserved than that of other blood-transmissible viruses such as human immunodeficiency virus or hepatitis C virus.

Amino Acid Sequence↗
PubMed1992

Identification of an endoflagellar associated protein in Borrelia burgdorferi.

DNA of Borrelia burgdorferi was cleaved by the endonuclease EcoRI and ligated with the bacteriophage expression vector lambda gt11. After infection of the Escherichia coli strain Y1089, the plaques of recombinant phages were screened with a B. burgdorferi antiserum (human) for fusion proteins containing borrelia antigen.s A positive clone produced a hybrid protein (p200) of c. 200 Kda. The corresponding native borrelia protein (p97) was identified as having an Mr of 97 Kda. To localise protein p97 in the B. burgdorferi cell, immunoelectronmicroscopy and a Western blot of isolated flagella were used. Antibodies directed against proteins p200 and p97 recognised epitopes associated with the flagella.

Animals↗
PubMed1992

Nucleotide sequence of the ospAB operon of a Borrelia burgdorferi strain expressing OspA but not OspB.

The nucleotide sequence of a 1.6-kb clone containing the gene for outer surface protein A (OspA) of a German strain (GO2) of Borrelia burgdorferi was determined. The deduced amino acid sequence showed a homology of 82% to the OspA molecules from three other B. burgdorferi strains. The best-conserved region was recognized at the 36-amino-terminal amino acids of OspA. OspB could not be identified in the strain investigated, probably because the nucleotide sequence of the ospAB operon prevented expression of the OspB gene.

Amino Acid Sequence↗
PubMed1991

Occurrence of antibodies to L1, L2, E4 and E7 gene products of human papillomavirus types 6b, 16 and 18 among cervical cancer patients and controls.

Sera from 118 women of 33 to over 90 years of age, with or without a history of cervical squamous-cell carcinoma, were examined for the presence of antibodies to HPV-6b, HPV-16 and HPV-18, L1, L2, E4, and E7 gene products by the use of bacterially derived beta-Gal fusion proteins and Western-blot analysis. Among the cervical cancer patients, 29/46 (63.0%) were positive for antibodies to E4 and/or E7 of HPV-16 and/or E7 of HPV-18. In contrast, only 2 of 31 (6.5%) non-genital cancer patients and 4 of 41 (9.8%) healthy individuals were antibody-positive for HPV-16 E4 or E7, while antibodies to the homologous proteins of HPV-18 could not be detected. Prevalence rates of antibodies to the HPV-16/18 late proteins were 25/46 (54.3%) in the cervical carcinoma group, 13/31 (41.9%) among women with non-genital cancer types, and 18/41 (43.9%) among normal, healthy individuals. Antibodies to HPV-6b late gene products ranged between 6.5% and 12.2% in the different patient groups. Antibodies to HPV-6b E4 and E7 were detected only once. By studying an additional control group of 207 women with a different age distribution, age-dependence of antibodies to HPV gene products could be ruled out. Whereas antibodies to late proteins may indicate that, regardless of clinical stage, HPV infections are wide-spread among the female population, the striking difference between the prevalence rates of antibodies to early proteins of HPV-16 and HPV-18 among cervical cancer patients and controls (p less than 0.001) supports the idea of the involvement of these virus types in carcinogenesis of the cervix.

Adult↗
PubMed1991

Identification of an immunoreactive non-proteinaleous component in Borrelia burgdorferi.

Investigations of immunoblots using Borrelia burgdorferi antigen demonstrated that a band, migrating faster than the bromophenol blue front in sodium dodecyl sulfate-gel electrophoresis, reacted strongly with sera containing anti-Borrelia burgdorferi antibodies preferentially of the IgG class. Extraction of this antigenic component and chemical analyses showed that the substance was composed mainly of fatty acids and carbohydrates. Typical structures of classical lipooolysaccharides such as 3-deoxy-D-manno-2-octulosonic acid, hydroxy fatty acids or lipid A could not be detected.

Antibodies, Bacterial↗
PubMed1991

Antibodies to human papillomavirus type-16 in human sera as revealed by the use of prokaryotically expressed viral gene products.

Open reading frames of human papillomaviruses were expressed in Escherichia coli as beta-galactosidase fusion proteins. These bacterially derived papillomaviral gene products were used to examine sera from 67 women (63 healthy subjects, 4 patients with genital carcinoma) for antibodies to papillomavirus type-16 antigens (E1, E2, E4, E5, E6, E7, L1, L2) and the L2 proteins of HPV-6b and HPV-18 by Western-blot analysis. The serologic data were compared with cytological findings classified according to Papanicolaou and with nucleic acid hybridization data from cervical smears of the same individuals. Twenty-three of the normal individuals showed antibodies exclusively directed against L2 gene products; whereas in the sera from the four genital cancer patients, antibodies to the early gene products E4 and/or E7 could be detected. In one case these antibodies were found to be combined with antibodies to L2 of HPV-16 and -18 and in another case with those to E1 and E2 of HPV-16. In none of the sera examined could antibodies to L1, E5 or E6 be identified. Three of the antibody positive normal women were found to be also positive for HPV-16/18 DNA, while all of the 40 seronegative women were HPV-16/18 DNA negative. These data indicate that serology may be a valuable means to study the epidemiology of genital human papillomavirus infection.

Adult↗
PubMed1991

Identification of a binding site in the hepatitis B virus RNA pregenome for the viral Pol gene product.

The hepatitis B virus, although containing a DNA genome, replicates by reverse transcription of an RNA pregenome. The viral Pol gene encodes the reverse transcriptase which catalyzes viral DNA synthesis. To study the interaction of this protein with HBV RNA, the entire Pol gene product was expressed except its eight amino-terminal codons in Escherichia coli as fusion protein with beta-galactosidase. In the absence of competing nucleic acids full-length expression products were able to nonspecifically bind in vitro synthesized HBV RNAs of different polarity and length. However, if competed with an excess of unspecific RNA, only those HBV RNAs were bound which contained besides the direct repeats 1 and 2 nucleotide sequences downstream of direct repeat 1. The corresponding binding site was found to be located within the adjacent 134 nucleotides downstream of DR1. We conclude from our data that this region which is in part homologous to the U5 region of retroviral genomes may be important for the binding of the HBV Pol gene product to the viral pregenome.

Binding Sites↗
PubMed1991

Use of peroxidase-labelled antigen for the detection of antibodies to Borrelia burgdorferi in human and animal sera.

We have developed a modified ELISA for the detection of anti-Borrelia burgdorferi (Bb) antibodies based on a peroxidase enzyme labelled antigen (ELAT). Microtiter plates were coated with antigen of Bb. The immunoglobulins of the serum samples were bound to the antigen and specific antibodies were detected by an enzyme labelled antigen. The test principle facilitates the recognition of specific antibodies in different collectives of human and animal sera. We performed epidemiological studies with the ELAT on 231 sera from mothers in maternity wards (9.5% positive), 219 patient sera sent to the Bb routine diagnostics (15% positive) and 230 sera from forestry workers (21.3% positive). We further investigated sera from red deer from South Lower Saxony which remained 55% Bb-antibody positive; deer were 37% and fallow deer were 29% positive.

Animals↗
PubMed1990

[Infectious mononucleosis: hemolysis by autoantibodies against triosephosphate isomerase].

Generalized adenopathy and splenomegaly developed in an 18-year-old youth after a severe tonsillitis followed by headache, tiredness and weight loss for several weeks. Infectious mononucleosis (acute Epstein-Barr virus infection) was confirmed by the demonstration of virus-specific antibodies. A reticulocytosis (24%), decreased haptoglobin concentration (0.6 mg/dl) and increased lactate dehydrogenase activity (657 U/l) indicated marked haemolysis. The bone marrow showed increased erythropoiesis with abnormal maturation. Antibodies against triosephosphate isomerase and against blood group marker "i" were demonstrated in the patient's serum. Antibodies against triosephosphate isomerase from the patient's serum were purified by affinity-chromatography. They strongly reacted with the patient's erythrocytes and under complement activation induced an increased 51Cr liberation from marked erythrocytes. No corresponding effect of anti-i-antibodies was noted at 37 degrees C. With the fall in antibodies against triosephosphate isomerase the haemolysis receded and the patient became free of symptoms after 7 weeks.

Adolescent↗
PubMed1990

Autoantibodies against triosephosphate isomerase. A possible clue to pathogenesis of hemolytic anemia in infectious mononucleosis.

In sera from patients with acute EBV, infection and the clinical symptoms of infectious mononucleosis antibodies of the Ig class M were found that are directed against two cellular proteins. The molecular mass of these proteins was determined to be 29 (p29) and 26 kD (p26), respectively, in SDS-PAGE. P29 was identified as part of the glycolytic enzyme triosephosphate isomerase (TPI) by comparison of the NH2-terminal amino acid sequences. A purified antibody against TPI induces a 51Cr release from human erythrocytes. Possibly, anti-TPI causes hemolysis, which is an infrequent but serious symptom of infectious mononucleosis.

Amino Acid Sequence↗
PubMed1990

Assay of preS epitopes and preS1 antibody in hepatitis B virus carriers and immune persons.

The diagnostical significance of the large hepatitis B surface protein with its preS1 attachment site and of anti-preS antibodies are not yet well known. We investigated the epitope of the preS1 attachment site to see whether it is a marker of viremia and whether antibodies against it occur in convalescents and vaccinees. For comparison, sera were also tested for the presence and relative amount of a preS2 epitope. The epitopes were detected by binding to specific monoclonal antibodies (mAb MA18/7 for the preS1 epitope and mAb Q19/10 for the preS2 epitope) at the solid phase of a sandwich enzyme-linked immunosorbent assay. Antibody against the preS1 epitope was detected by inhibition of binding to mAb MA18/7. This mAb inhibits attachment of preS1 antigen to hepatocytes and reacts with a subtype-independent sequential epitope at the surface of hepatitis B virus between amino acid 29-36. This preS1 epitope occurs in most hepatitis B surface antigen (HBsAg) carriers, irrespective of viremia. Free preS2 epitope Q19/10 is present in samples with more than 8 micrograms/ml total HBsAg and it is masked in sera with less HBsAg. Antibodies which compete with mAb MA18/7 for its viral preS1 epitope occur in one third of HBsAg carriers who were negative for hepatitis B e antigen. It also occurs in one third of convalescents and in most good responders to plasma-derived vaccines.

Antibodies, Monoclonal↗
PubMed1990

Expression of an antigenic polypeptide of the human parvovirus B19.

The DNA fragment of the human parvovirus B19, with 715 nucleotides between nucleotide positions 3141-3856 was expressed in Escherichia coli as a beta-galactosidase fusion protein. The plasmid vector pSS20d used for this purpose permits cleavage of the viral gene product from the beta-galactosidase moiety by collagenase. After purification by p-aminophenyl-beta-D-thiogalactoside-sepharose and superose, a soluble protein with a molecular mass of 28 kDa was isolated. It represents a common part of the viral capsid proteins VP1 and VP2. This bacterially derived parvoviral gene product can be used for detection of anti-B19 antibodies in human sera.

Antibodies, Viral↗
PubMed1990

Occurrence of human papillomavirus DNA types 16 and 18 (HPV-16/18) in cervical smears as compared to cytological findings.

Cervical smears from 2336 women were examined for the presence of HPV-16/18 by dot-blot hybridization using 32P-labeled HPV-16/18 DNA under high stringency conditions. The hybridization data were compared with cytological findings classified according to Papanicolaou. The ages of the patients ranged from under 20 to over 70 years. Ninety-eight (4.4%) of the 2237 cytologically normal cervical samples (Pap I and II) were HPV-16/18 positive. Thirteen out of 32 (40.6%) samples showing signs of mild and moderate dysplasia (Pap IIID) were found to be HPV-16/18 positive. In 5 out of 7 (71.4%) samples from women with severe dysplasia or carcinoma in situ (Pap IV) and in 9 out of 25 (32.1%) samples from patients with invasive cervical carcinoma (Pap V) HPV-16/18 DNA was detected. Thirty-two smears were from women with severe unspecific cervical inflammation (Pap III). Two (6.2%) out of them were HPV-16/18 positive. Normal smears showed an apparent age-dependent pattern of HPV-16/18 positivity with a peak prevalence of 10.6% among women younger than 20 years old. The majority of premalignant lesions was detected among women younger than 40 years old; whereas all invasive lesions were from women older than 39 years. Compared to the HPV-16/18 prevalence rate in normal smears, abnormal smears harbored HPV-16/18 DNA approximately 9 times more frequently. This finding supports the hypothesis that HPV-16/18 may be involved in the development of cervical cancer.

Adult↗
PubMed1990

Protective potential of hepatitis B virus antigens other than the S gene protein.

The current recombinant hepatitis B vaccines are safe and effective. However, the occurrence of non-responders and difficulties in immunizing immunodeficient persons suggest the need for further improvements. Recent data suggest that the pre-S2 and pre-S1 domains of hepatitis B virus induce protective antibodies. The good T-helper cell response against pre-S1 epitopes would also improve the antibody response against the small surface antigen protein. An even better T-cell priming could be achieved by including hepatitis B core (HBc) proteins or peptides. An optimal immunogen would contain all three proteins comprising hepatitis B surface antigen in their natural conformation and glycosylation as well as the major T-cell epitopes of HBc.

Animals↗
PubMed1990

Peripheral facial palsy in childhood--Lyme borreliosis to be suspected unless proven otherwise.

27 consecutive cases with acute peripheral facial palsy were studied for Lyme borreliosis. In 16 out of 27 children Lyme borreliosis could be diagnosed by detection of specific IgM antibodies in CSF. CSF findings allow a clear distinction according to etiology. All children with facial palsy due to Lyme borreliosis revealed lymphocytic CSF pleocytosis, whereas in cases of unknown etiology CSF was usually normal. Bilateral facial palsy occurred only in children with Lyme borreliosis. All cases with a positive history of tick bite and/or erythema migrans in the head-neck region showed ipsilateral neurological affection suggesting a direct invasion via the affected nerve by Borrelia burgdorferi.

Adolescent↗
PubMed1990

IgM autoantibodies against two cellular antigens always appear in acute Epstein-Barr virus infection.

In the course of infectious mononucleosis, IgM antibodies are formed against 2 proteins present in nucleated and non-nucleated vertebrate cells. Antibodies were found in sera of all patients suffering from acute Epstein-Barr virus infection. In 40% of the cases these antibodies are monoclonal. Persons with former Epstein-Barr virus infection were negative. The antibodies against the 2 proteins were first detected in Raji cells with an IgM-specific immunofluorescence test. The proteins were demonstrated in extracts of different cells and tissues by immunoblot technique. The molecular weight of the proteins measured in SDS polyacrylamide gel electrophoresis was 26 kd and 29 kd, respectively. Their presence in the cells does not depend on the presence of the Epstein-Barr virus genome. The relevance of the new findings concerning diagnostics as well as pathogenetic aspects remains to be established.

Antibodies, Viral↗